The present invention relates to fuel channels used to encase fuel bundles in a boiling water nuclear reactor (BWR). The invention specifically relates to computer systems that depict and analyze the fuel channels.
A Boiling Water Nuclear Reactor (BWR) generates power from a controlled nuclear fission reaction. As shown in FIG. 14, a simplified BWR includes a reactor chamber 101 that contains a nuclear fuel core and water. Generated steam is transferred through pipe 102 to turbine 103, where electric power is generated, and the water returns to the core through pipe 104. A control computer 106 may control the operation of the BWR and particularly its core.
In the BWR core, fuel rod bundles are encased in thin rectangular fuel channels. A fuel channel may be embodied as a hollow box within which are arranged the fuel rod bundles. Fuel channels can deform. They may deform due to various nuclear and mechanical responses in the core of an operating BWR driven primarily by plant operation strategy. The nuclear and mechanical responses are complex and spread out over time. For example, the operation of a channel (the “cause”) may result in channel deformation (the “effect”) observed later in the residence time of the channel in the core.
A deformed channel can adversely affect the performance of the core. For example, a deformed fuel channel can inhibit the movement of control blades through the core. On the other hand, a deformed fuel channel at another location may not interfere with control blades or cause difficulties.
Channel deformations can lead to channel-control blade interference (e.g. cell friction), which may hinder the control blade operation. Control blades in a BWR are actively used for safe and efficient operation. Any hindrance that affects plant safety or licensing bases may require undesirable mitigating actions. Therefore, cell friction needs to be adequately managed as part of reactor cycle design, optimization, licensing, and monitoring.
An added complexity is that after a specified period of operation (for example, 18 to 24 months), the core is refueled and transitions to a new operating cycle. As part of refueling, channels are shuffled in the core. The shuffling typically results in substantial changes in the operation and interactions of the channel. For example, a deformed channel that causes no difficulty in one location may be inadvertently moved to another location in the core where the channel deformation interferes with a control blade.
Channel distortion and cell friction phenomenon are typically addressed within the context of an operating nuclear reactor cycle design, optimization, licensing, and monitoring. Channel deformation affects many operational and safety parameters. Deformations are typically addressed as part of reactor cycle design, optimization, licensing and monitoring. Information regarding deformed channels is collected and available. However, conventional methods used for design, optimization, licensing, and monitoring of a nuclear reactor do not provide a graphical user interface (GUI) format to address channel distortion and cell friction. Accordingly, there is a long felt need for a tool to assist BWR users and designers in addressing channel deformation issues.